There is an increasing commercial importance and need for systems that are capable of automatically reading and identifying of cargo containers and for keeping track of the individual containers in a container terminal or after having been loaded/unloaded to/from a ship, train or the like.
In modern terminals, the flow of containers is normally registered at the gate. All cargo or freight containers are each provided with a unique identification marking or code, ID, that must be checked and verified. The container ID is recorded by the terminal logistics in order to create a later shipping instruction for sending the container out on a ship, train or the like by using a handling apparatus such as a crane. In order to minimize mistakes and “loosing” containers, all containers also have to be assigned when and to where the container is loaded/unloaded.
For containers being loaded/unloaded to or from a ship or a train, such ID are read and handled manually by an operator and entered manually into a computer system for controlling operations in the cargo container terminal.
There are several problems with this. Both true position of storage in the ship or on the train, the sequence and the collection from trucks is frequently erroneous compared to the logistic instruction. Manual systems are also clearly inefficient as it is time consuming and errors more easily occur i.e. when data manually is entered into computer systems. If a container is lost or subject to wrong routing or just misplaced lead to unnecessary time delays for finding it, which creates unwanted and unnecessary costs.
Every container that is loaded or unloaded from a truck, between the legs or in the backreach of a quay crane, must pass the sill beam height level of the crane. The time when this is done, the size of the container passing and the exact position where the driver may pass this level is unknown. All kinds of odd moves or shuffle relocations made by the driver on ship or over quayside that do not result in a “complete job”, that is transferring a container on or off the ship, may happen and the same container may pass the sill beam height level several times. It is a problem to identify or detect incomplete job moves, i.e. if a container is moved but did not result in a “job complete”, i.e. the container were not completely loaded or unloaded.
Truck travel direction and final position while being loaded or unloaded is also unpredictable. Other trucks may as well be passing the truck being served by the crane and may then be blocking the side view of the container.
The container ID should always be checked when the crane finished the job and the time should be logged and related to the crane or ship/train position, linked to the container ID and returned to the terminal logistics via a printer, a data log, a network, a radio link or a display.